Proposals have been made to provide a system for guiding an vehicle to a prescribed parking space as can be found in Japanese patent laid-open publications Nos. 2003-104220, 2000-072019 and 2003-339060. Such a parking guide system typically comprises an onboard camera for capturing the image of the area around the parking space to acquire the information required for guiding the vehicle. However, to obtain the image information and other data required for guiding the vehicle solely from the end of the vehicle, cameras, various sensors and a control unit that are highly expensive are required to be mounted on the vehicle, and this adds to the cost of the vehicle to an unacceptable extent.
On the other hand, if a robot that can move about in the parking lot is used for guiding each vehicle, the vehicles are not required to be provided with any expensive guide system, and the required overall cost can be minimized. For this purpose, the robot is required to be equipped with a camera for capturing the image of the vehicle and parking spaces and a control unit for obtaining the necessary information and providing an appropriate guidance to each vehicle.
The assignee of this application previously proposed robot systems that could be applied to a robot system for guiding an vehicle to a prescribed parking space as can be found in Japanese patent laid-open publication No. 2004-094288 that discloses a device for analyzing the image of an object for the purpose of obtaining information on the object and Japanese patent laid-open publication No. 2004-171165 that discloses a system for recognizing a moving object at a high precision.
Oftentimes, the parking space may not be very spacious, and it may not be easy for a motorist to park the vehicle. Curbside parking and backing into a parking space from an oblique angle are known to cause some difficulty to inexperienced motorists. In such cases, properly selecting the steering angle at each moment is highly important for successful parking. It is therefore desired that a robot is able to give a proper guidance on the steering angle to the motorist at each moment in such a manner that the motorist can follow the guidance without difficulty.